Neural network in Py

test2.py

from random import random
import math


def dot(a, b):
    return sum([k * v for k, v in zip(a, b)])


def sig(x):
    return 1 / (1 + math.exp(-x))


class NNTest:

    def __init__(self, inputs, outputs, layers):
        self.w = []
        c = inputs
        for n in layers + [outputs]:
            wi = [[random() * 2 - 1 for _ in range(c)] for _ in range(n)]
            self.w.append(wi)

    def calc(self, x):
        v = x
        for wi in self.w:
            v = [sig(dot(v, wij)) for wij in wi]
        return v


if __name__ == '__main__':
    nn = NNTest(2, 1, [4, 3])
    print(nn.calc([-0.5, 0.5]))